Manual wheelchair propulsion on ramp slopes encountered when boarding public transit buses

Objective: To compare the kinetics of manual wheelchair (MWC) propulsion on ramps of varying slopes that may be encountered when accessing large accessible transit vehicles (LATVs). Design: Observational study. Setting: Biomechanics research laboratory. Participants: A convenience sample of able-bodied adults (n = 7) having no propulsion experience propelled a MWC on ramps of slope 3.5°, 9.5° and 15°. Interventions: Not applicable. Main outcome measures: Resultant (F_res), radial (F_r) and tangential (F_t) forces applied to the wheelchair pushrim, rate of rise of resultant force (ROR), peak power output (P), temporal characteristics and thigh to trunk angle were analyzed across three ramp slopes. Results: Pushrim forces and power output significantly increased with increasing slope, with peak F_res more than doubling from 107 N on a 3.5° slope to 230 N on a 15° slope. ROR was 1.76 times higher at 9.5° and 2.47 times higher at 15° compared to a 3.5° slope. Minimum thigh to trunk angle decreased sharply from 80° (3.5° slope) to 50° (9.5° slope) and then to 30° (15° slope) as ramp slope increased. Conclusions: Ascending bus ramps require greater power and pushrim force on steeper ramp slopes, presenting a potential barrier to transportation accessibility. Given this finding, it is imperative that bus operators minimize ramp slope to assure MWC users are able to access LATVs. Implications for Rehabilitation Although transit bus ramps are intended to provide wheelchair access to public transportation, limitations in MWC user physical strength and function may prevent safe access. Transit bus ramp slopes encountered during ingress can present a challenge to MWC users given power output and pushrim force requirements to ascend the ramp. MWC users and therapists should be aware of ramp slopes that may be encountered when boarding transit buses; wheelchair training should incorporate skills needed to ascend transit bus ramps.